04.28.2016
Written By: Zoe Christenson Wick
This week we built off of our Cell Biology & DNA exploration by focusing on my favorite cell type: neurons! Neurons are the cells in your brain and entire nervous system that make you who you are. Neurons control your movements, carry information about your sensations and perceptions, and allow you to learn and remember (and much, much more!). Neurons communicate with each other using electrical and chemical signals that are passed from neuron to neuron through gateways called synapses. The strength of these synapses, or connections, changes with one’s experiences. The highly influential psychologist Donald Hebb came up with a postulate known as Hebb’s Postulate is often summarized as, “Cells that fire together, wire together.” In other words, two neurons that communicate with each frequently will have stronger synapses than two neurons that rarely communicate with each other. The ability of neurons to change their synaptic strength is known as neural plasticity.
Neural plasticity is a phenomenon constantly occurring in one’s brain. For instance, the more you practice a task – such as learning a language – the stronger your ‘language-learning’ neurons become. Once you stop practicing that language those neurons become weak again.
To test neural plasticity in the classroom, we used a prism goggle experiment to challenge the brain and induce neural plasticity. In this experiment, students try to throw a bean bag into a bucket 10 times. This should be challenging, but do-able. Then, they put on the prism goggles, which shift your vision left or right, and again they try to throw the bean bags into the bucket. The students watching will notice that, initially, the student throwing will miss (by a lot) in the direction their vision was shifted. Over the course of 10 throws, the student throwing will adapt their movements, throwing the bean bags closer to the target. This adaptation is neural plasticity.
After throwing the bean bags with the prism goggles on, the student will take the prism goggles off and try again. In my opinion, this is the most exciting part of the experiment. Because, while wearing the prism goggles, your neurons have learned and adapted to a new relationship between your muscle movements and your vision. When you take off the goggles, your neurons must re-adapt and re-learn the old relationship between your muscle movements and your vision. This is illustrated in the experiment when students miss the target in the opposite direction than they did while wearing the goggles. In my experience, measuring the effect of re-learning the old relationship between your visual sense and your sense of proprioception (your sense of where your body is in relation to the space around you and relative to other parts of your body) is much more sensitive than measuring the adaptation while wearing the goggles. To increase the likelihood of seeing that second adaptation effect, we encouraged the students to keep the prism goggles on right up until they started throwing the third set of bean bags (so they would have less time to get used to their visual sense).
For the sake of time, we had each student throw the bean bags 10 times before goggles, 10 times during goggles, and 10 times after goggles with as little movement in between bean bag tossing sessions as possible. However, if so inclined, you could explore with time and movement as variables. If you keep the prism goggles on for a longer time, what happens? What would happen when you took them off after wearing them for 20 minutes? What if you walked around a lot or practiced tossing the bean bag to yourself while wearing the goggles?
Overall, I think this experiment was a success. While we didn’t get much time to explore with many variables, I think this was a good lesson in data collection, experimental design, and understanding graphs and figures.
Until next time!